Justin sent 24 text messages on Monday, 48 on Tuesday, 36 on Wednesday, and 22 on Thursday. Use mental math to find the total number of messages he sent during the four days. Explain

It's easiest to find numbers that add up to 10.

Try and add up 24 and 36 because you know that 6+4=10

so you get 6+4 and then do 20+30, add those together and you get 60

Then do the same for the other two numbers

8+2 and 40+20, add those together and you get 70

Add up 60 and 70 and you get 130 text messages.